NBFM Transmit

Narrow Band FM Transmitter.

Takes a single float input stream of audio samples in the range [-1,+1] and produces a single FM modulated complex baseband output.

The only difference with WBFM Transmit is the size of the internal low pass filter for interpolation. Here it has a cutoff frequency of 4.5kHz with 2.5KHz of transition width.

Parameters

(R): Run-time adjustable

Audio rate

Sample rate of audio stream, >= 16k (integer)

Quadrature rate

Sample rate of output stream (integer). Must be an integer multiple of Audio rate.

Tau

Preemphasis time constant (float)

Max deviation (R)

Maximum deviation in Hz (float)

Preemphasis High Corner Freq

High frequency at which to flatten preemphasis; < 0 means default of 0.925*Quadrature rate/2.0 (float)

Example Flowgraph

This flowgraph shows a signal source feeding a Narrow Band FM modulator driving a PlutoSDR Sink block.

Source Files

Python files

[1]

Block definition

[2]